Vehicle simulator with low frequency sound feedback

ABSTRACT

A driver training system for a user of a simulated vehicle. The system includes input devices for controlling the simulated vehicle, a video display having three dimensional graphics, a computer, modeling software for determining position information based on the input devices, atmospheric effects software to simulate time-of-day and weather conditions, and realistic operating feedback software for simulating on the input devices the feedback normally experienced with operating the vehicle. One aspect of the preferred embodiment is a system including a low frequency speaker mounted on an enclosure adjacent to the simulation user&#39;s seat through which road feel cues such as hitting an object are transmitted to the user in response to signals received from the computer. Another aspect of the invention is the a system for simulating the feel to the user of anti-lock brakes on a brake pedal in response to signals received the computer.

RELATED APPLICATIONS

This application is a division of application Ser. No. 08/018,950, filedFeb. 17, 1993, entitled "Vehicle Simulator with Realistic OperatingFeedback," now U.S. Pat. No. 5,368,484 which is a continuation-in-partof application Ser. No. 07/888,375 filed May 22, 1992, entitled "DriverTraining System and Method with Performance data Feedback" now U.S. Pat.No. 5,366,376.

MICROFICHE APPENDIX

A microfiche appendix containing computer source code is attached. Themicrofiche appendix comprises three (3) sheets of microfiche having 149frames, including one title frame.

The microfiche appendix contains material which is subject to copyrightprotection. The copyright owner has no objection to the reproduction ofsuch material, as it appears in the files of the Patent and TrademarkOffice, but otherwise reserves all copyright rights whatsoever.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to vehicle simulators and, moreparticularly, is concerned with realistically simulating to the user thefeeling of the vehicle controls and the vehicle ride as it moves withinthe simulated universe.

2. Background of the Invention

A vehicle simulator can be defined as a system that simulates theoperating conditions of a vehicle in an environment. Where the vehiclesimulated is an automobile, the vehicle will usually include the typicalautomobile controls such as a steering wheel, a gear shift, anaccelerator pedal, and a brake pedal. Generally, this vehicle will besimulated in an environment which will typically include a road.

Vehicle simulators provide a means to efficiently train operators of avehicle. The operator of a vehicle can safely learn, from the simulator,how the vehicle will operate in a given set of conditions withoutactually exposing the operator to any of the risks inherent in realworld operation of the vehicle. The experience garnered through makingmistakes on a simulator is invaluable when compared to the inherentrisks of vehicle damage and operator injury associated with making adriving error in a real-life situation. For example, in a policetraining application, a student could learn the limits of a policecruiser or guidelines for pursuit, and be tested in these areas withoutany of the associated risks of real-life training.

In addition to concerns relating to operator safety and vehicle damage,training through actual vehicle operation has other pitfalls. Inparticular, the cost of instructor time may be prohibitive. Furthermore,a specific vehicle such as a space or underwater vehicle, may simply notbe available for training purposes.

To enhance the effectiveness of the training afforded by vehiclesimulators, there is a need to ensure that the simulator realisticallysimulates both the feel of operating the vehicle, as well asrealistically simulating the effect of operating the various vehiclecontrols, in specific situations. Realistically simulating the feel ofoperating a vehicle includes simulating the feel of the vehicle as ittravels in a simulated environment as well as simulating the feel of thevarious vehicle controls during actual usage.

In automobile simulators the effectiveness of the training given by thesimulator would be enhanced if the simulator could translate to theoperator the feeling of a wide variety of road surfaces and objects thatan automobile is likely to come in contact with. Specifically, there isa need for a system that will generate a wide variety of road feel cuesbased on where the simulated automobile is within a simulated universeand what the simulated automobile contacts within that universe.

One example of where a prior art simulator has attempted to simulate thefeeling of a vehicle operating in an environment is shown in U.S. Pat.No. 4,574,391 to Morishima. Morishima discloses a sound system for avideo game, configured for giving a live action feeling to a gameinvolving artillery. This sound system includes several audio speakersmounted around the user's head as well as a low frequency speakermounted underneath the user's seat. The live action feeling is generatedby having the audio speakers generating artillery sound in sequencethereby creating the illusion of the artillery shell approaching and,when the round hits, sending low frequency components of the explosionsound to the low frequency speaker mounted underneath the user's seat.The low frequency speaker then causes the seat to vibrate as a directresult of an explosion sound.

One shortcoming of the system disclosed in Morishima is that the seatvibration and the sound of the explosion are not generatedindependently. That is, the vibration is a direct result of the lowfrequency components of the sound of the explosion. Generating physicalfeedback by transmitting the low frequency component of an associatedsound limits such feedback to only sound events having a sufficientlylarge low frequency component to cause the seat to vibrate.Consequently, the feel of events which occur during the simulation whichdo not have a large low frequency component cannot be represented to theuser. Hence, there is a present need for a system which is capable ofsimulating a vehicle in a specific environment and, which is capable ofproviding physical feedback based on a variety of simulated events whichare not always accompanied by a sound including a large low frequencycomponent.

In automobile simulators, the effectiveness of the training given by thesimulator would be further enhanced if the feel of the brake pedal tothe operator closely approximated the feel of an actual brake pedal inan actual car when the brake pedal is depressed. Further, the effect ofdepressing the brake pedal a given amount in the automobile simulator,as perceived by the operator (or user), should also closely approximatethe effect that depressing the brake pedal the same amount has in areal-life automobile.

Many of today's automobiles are equipped with Anti-Lock Brake (ABS)systems. An ABS system is a safety feature added to automobiles toenhance the controllability of automobiles during braking maneuvers.When non-ABS brakes are suddenly applied, or applied with great force,the brakes may lock up and consequently the automobile will often enterinto an uncontrollable skid. An automobile tire will skid over pavementwhen the forward momentum of the automobile exceeds the velocity of thetire, thereby dragging the tire forward over the pavement in a skiddingfashion. An ABS braking system acts to prevent such uncontrollable skidsby sensing when the tire is being dragged over the pavement, and thendecreasing the amount of stopping pressure exerted by the brakes againstthe wheel by an amount just sufficient to permit the tire to continue toroll over the pavement while still slowing the rotation of the tire. TheABS system will then typically oscillate between increasing anddecreasing the amount of braking force exerted against the tire as theABS system tries to slow the rotational velocity of the tires, whilealso preventing the brakes from locking up. This oscillation results ina unique, vibratory pulsation of the brake pedal during braking.

Currently, no known vehicle simulators simulate the feel, or the effect,of ABS brakes. However, a person driving an automobile equipped with ABSbrakes may become startled when they first experience the feeling of abrake pedal of a vehicle which is equipped with ABS brakes and, as aconsequence, stop braking the vehicle when braking is necessary. Hence,the lack of a simulator which will simulate an automobile equipped withABS brakes represents an additional shortcoming in the prior artrelating to driving training simulators.

SUMMARY OF THE INVENTION

The aforementioned needs are satisfied by the present invention which isimplemented on a driver training system for a user of a simulatedvehicle. This driver training system is comprised of a plurality ofsimulated input devices for controlling the operation of the simulatedvehicle, and includes a video display for presenting the user with aview of a simulated environment, and a means responsive to the inputfrom the input devices for modeling the position and the operatingcharacteristics of the vehicle within the simulated environment.

In one preferred embodiment of this invention the simulated vehicle isan automobile. The system of this embodiment includes means fordetermining when the vehicle in the simulated universe is at a pointwhere a road cue should be transmitted to the user. At this point thesystem recalls a digital signal of the road cue out of a memory,translates it into an analog signal, which is then low pass filtered andamplified. The amplified low frequency signal is then sent to a lowfrequency speaker where the speaker's diaphragm is in communication witha body of air confined within an enclosure coupled to a user's seat. Thesignal will then cause the speaker diaphragm to vibrate which in turncauses the air within the enclosure to translate and be compressed. Thecompression and translation of the air within the enclosure causes asemi-rigid diaphragm consisting of a piece of flexible material, whichis an integral part of the enclosure, to vibrate. Since the seat uponwhich the user sits is coupled to the semi-rigid diaphragm, vibrationsof the semi-rigid diaphragm will be felt by the user.

In another aspect of this invention, there is a system which isconfigured for use with automobiles, which will sense when the user ofthe simulator has applied the brakes in such a manner that an ABSbraking system would be activated in a real-world automobile. Thissystem then will induce mechanical vibrations and pulsations on thebrake pedal, to simulate the brake pedal response that occurs under thesame braking conditions in a real-world automobile that is equipped withABS brakes.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of one presently preferred driver trainingsystem of the present invention;

FIG. 2 is a perspective illustration of a user's view while maneuveringthrough a lane change course on a steering track corresponding to avideo screen display provided by the driver training system of FIG. 1;

FIG. 3 is a flow diagram of the "executive₋₋ control" function whichforms a portion of the control process shown in FIG. 1;

FIG. 4 is a diagram of a set of mechanical input devices and aninstrument panel for the simulated vehicle of the driver training systemshown in FIG. 1;

FIG. 5 is a side elevational view of one presently preferred embodimentof a seat and low frequency speaker assembly for the driver trainingsystem wherein the speaker is mounted in a floor mounted base, shown incross-section, under the seat;

FIG. 6 is a top plan view of the base of the low frequency speakerassembly taken along line 6--6 of FIG. 5;

FIG. 7 is an electrical schematic showing one presently preferredembodiment of a relay control circuit which is connected to the lowfrequency speaker shown in FIG. 5;

FIG. 8 is a side elevational view of another presently preferredembodiment of a seat and low frequency speaker assembly for the drivertraining system of the present invention wherein the speaker is mountedin the back of the seat; and

FIG. 9 is a cross-sectional side view of the mechanical structure of onepresently preferred embodiment of an ABS brake simulation assembly ofthe present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Reference is now made to the drawings wherein like numerals refer tolike parts throughout.

FIG. 1 shows one presently preferred embodiment of a driver trainingsystem 100 of the present invention. The driver training system 100 isoperated by a user 102 (shown schematically), who desires to improvedriving performance. It should be understood that the driver trainingsystem 100 as hereinafter described is applicable to any type of vehiclethat is operated by a human. The present invention includes simulationswhich are easily generalized to driver training systems for all kinds ofsimulated vehicles and all types of driving.

The more specific embodiment of the driver training system 100 aspresented in the following figures and description comprises a vehiclesimulator for police training. At times, the user 102 can be aninstructor or a student.

In FIG. 1, the user 102 preferably sits in a booth or housing (notshown) such as the one described in the assignee's U.S. patent entitled"Rear Entry Booth and Adjustable Seat Apparatus for a Sit-Down ArcadeVideo Game," U.S. Pat. No. 4,960,117. In that way, distractions areminimized and the user 102 can concentrate on self-improvement of hisdriving technique.

In the driver training system 100, the user 102 moves a turn signallever 104, manipulates a plurality of dash and column switches 105,manipulates a key turned ignition switch 107 for starting the simulatedautomobile, depresses a brake pedal 106 which is part of an ABS brakesimulation system 500 and depresses a gas pedal 108 in the customarymanner. In addition, an automatic transmission shifter 110 ismanipulated by the user 102 to select a reverse gear or one of aplurality of forward gears. A steering wheel 112 is turned by the user102 so as to guide the simulated vehicle in the desired direction oftravel.

The mechanical inputs provided by the user 102 to the input devices 104,105, 108, 110 and 112 are translated by transducers into electricalsignals which are fed into a computer 114. The mechanical inputs on thebrake pedal 106 are translated into electrical signals by the ABS brakesystem 500 and the signals are fed to a bridge interface circuit 546connected to the computer 114. The computer 114 further receives bothinputs and downloaded programs from a personal computer (PC) 103 whichis preferably an IBM compatible computer having a 100 megabyte harddrive and a 4 megabyte RAM. The personal computer 103 and the computer114 are interactively connected via a communication link 140. The link140 should be capable of handling high speed digital data transmissions,on the order of 10 megabits per second, and it preferably includes acommunication circuit such as an ADSP 2105 or 2101 manufactured byAnalog Devices to ensure sufficiently rapid communication between thecomputer 114 and the personal computer 103.

In the presently preferred embodiment, the computer 114 includes ageneral purpose microprocessor such as a Motorola 68000 (not shown) oranother member of the Motorola 680x0 microprocessor family. One functionof the 68000 microprocessor is palette manipulation. In addition to the68000 microprocessor, the computer 114 preferably includes a modelprocessor (DSP), such as an AT&T DSP32C, a digital signal processor(ADSP), such as an Analog Devices ADSP-2101, and a graphics processor(GSP) such as a Texas Instruments 34010 Graphic System Processor, noneof which are shown. The DSP performs velocity, acceleration, andposition calculations. The ADSP provides the "higher-level" functions ofvideo display such as translation, rotation, scaling, and shading whilethe GSP efficiently performs dither patterning, rendering, and thelow-level graphics work of writing polygons (so-called polygon graphics)to the video display 122.

The presently preferred computer 114 also includes a read only memory(ROM) comprising 256 kilobytes of storage for self test; as well as arandom access memory (RAM) comprising: 1.75 megabytes for downloadedprograms, object definition data, and graphics universe data, anadditional 0.5 megabytes of shared memory for additional downloadedgraphics object data, shared with the 68000 processor. The centermonitor in the video display 122 (FIG. 1) also includes an additional 1megabyte of RAM for downloaded scenario traffic data. Furthermore, thepresently preferred computer 114 also incorporates additional randomaccess memories for each processor as follows: DSP--64 kilobytes;ADSP--12 kilobytes of program memory (for the programs downloaded fromthe personal computer 103), 16 kilobytes of buffer memory; and GSP--45kilobytes of program memory (for the programs downloaded from the RAM orthe personal computer 103) and 640 kilobytes of display memory. The GSPfurther employs video random access memory (VRAM) for improved videodisplay rates.

The computer 114 executes computer software which is stored in a memory(not shown) such as a 128×8K, 70-100 nsec Random Access Memory (RAM).The software executed by the computer 114 that is stored in this RAM canbe one of a number of software scenarios of programs relating to drivingstored within the PC 103 which can be downloaded into the RAM inresponse to commands executed at the PC 103. The computer softwareexecuted by the computer 114 is logically organized to include a controlprocess 120.

The control process 120 receives digitized signals from the inputdevices 104-112 as well as other digitized input signals from thepersonal computer 103. The control process 120 then passes data fromthese digitized signals, across a data path 118, to a model process 116that models the velocity and acceleration vectors of the simulated car.Thus, at a time T, position data, i.e., the Cartesian coordinates of thecar, are determined by the model process 116. The position data is madeavailable, across the data path 118, back to the control process 120.Accordingly, the control process 120 applies the "rules of the road" tothe new position of the car, and initiates signals to drive a videodisplay 122, a pair of speakers 123 and 124, a low pass filter 454 andan instrument panel 130. The filter 454 provides a low pass filteredsignal to an amplifier 450 which is connected to a relay 452, which inturn is connected to a speaker 430 positioned adjacent to a user's seat402 (FIGS. 5 and 8). The relay 452 is preferably a low voltage relaymanufactured by Potter & Brumfield, model no. T70L5D, and is furthercoupled to a relay control circuit 456 which disconnects the speaker 430when the system 100 is either powering up or down.

The control process 120 further provides a user viewpoint into agraphical representation of the vehicle universe. In the preferredvehicle simulation embodiment, the computer 114 generates polygongraphics to the video display 122. One preferred video display device,such as model no. 25K7191 available from Wells-Gardner of Chicago, Ill.,is a multi-synchronous display that can be configured to display 512×288pixels. The video display 122 may include a plurality of video devicesarranged in a semi-circle to give the user 102 a simulated view similarto that of a real car. This arrangement is described in the assignee'scopending U.S. patent application entitled "Modular Display Simulator,"Ser. No. 07/704,373

The video display 122 preferably generates a color, three-dimensionalgraphical representation of the environment, i.e., the user'sperspective of a graphical universe including items such as a roadway.The speakers 123 and 124 produce sounds such as gear changes, enginerevving, skidding, and so on. The low frequency speaker 430 ispreferably mounted adjacent to the seat 402 (FIG. 5) to simulate feel ofthe road. The instrument panel 130 includes a speedometer to indicatethe speed of the simulated vehicle, an indicator for the gear selectedby using the shifter 110, left and right arrow lights to indicate adirection selected by using the turn signal lever 104, and various otherindicator lights. Thus, the user 102 is presented with real-timefeedback from the output devices 122, 123, 124, 130 and 430 that ispersonalized according to his own individual performance and what heencounters in the simulated universe.

The control process 120 further provides feedback to simulate thefeeling of a steering wheel in a real automobile while being driven.This is preferably accomplished in the same manner as described inassignee's patent "Control Device such as a Steering Wheel for VideoVehicle Simulator With Realistic Feedback Forces", U.S. Pat. No.5,044,956. The control process 120, in response to inputs from the ABSbrake system 500 via a bridge interface circuit 546, also providesfeedback to the brake pedal 106 with the ABS brake system 500 therebysimulating the feeling of brakes on an automobile equipped with an ABSbraking system on the brake pedal 106.

The basic operation of the simulator system 100 will now be described. Asimulation program is downloaded from the personal computer 103 to thecomputer 114 which will execute the program. The computer 114 thengenerates a graphics universe to be displayed to the user 102 via thevideo display 122 along with associated sounds via the speakers 123,124. The user 102, in response to what he sees in the video display 122and what he hears from the speakers 123, 124 manipulates the drivingcontrols to thereby drive the simulated vehicle. Basically, the user 102starts the automobile via the ignition switch 107, puts the automobilein gear via the automatic transmission shifter 110, depresses the gaspedal 108 to make the automobile move, depresses the brake pedal 106 tomake the car stop and steers the automobile with the steering wheel 112.

In response to the user inputs provided via the input devices 104-112,the control process 120 of the computer 114 passes data to the modelprocess 116 via the data path 118 which enable the model process 116 tomodel the velocity and acceleration vectors of the simulated vehiclethereby determining the Cartesian coordinates of the vehicle. This datais then passed back to the control process 120 via the data path 118 andis then used by the control process 120 to provide additional signals tothe user 102. For example, the Cartesian coordinates as determined bythe model process 116 may determine that the user 102 has driven thesimulated vehicle over a cone in the simulated universe, hence thecontrol process 120 causes the speaker 123, 124 to generate anappropriate noise, cause the feeling of hitting a cone to be generatedand felt by the user 102, via the low frequency speaker 430, as well ascause the steering wheel 112 to vibrate in the hands of the user 102 inresponse to hitting the cone. Further, the control process 120 will alsoprovide feedback to the user 102 through the ABS brake system 500 whenthe user 102 applies the brakes sufficiently hard to enable the system.

FIG. 2 is a diagram of a video screen display showing one example of acourse upon which the user 102 (FIG. 1) may operate the vehicle. Fromthe first person viewpoint of FIG. 2, it is seen that the user 102 is"placed inside" of the vehicle being simulated. The user 102 views athree-dimensional simulated graphical universe 139 as projected onto thetwo dimensional screen of the video display 122. The scene representedin FIG. 2 is one wherein the user 102 is looking forward out of awindshield while driving the simulated vehicle and proceeding on thetrack.

In this embodiment of the present invention, the user 102 is presentedwith a course 142, which is a specific instance of the universe 139. Theuser 102 has the basic objective of trying to drive through the courseat a desired speed without hitting any obstacles, i.e., a configurationof cones 143. The computer 114 will also cause an appropriate backgroundto be displayed. In the illustrated case, this is a cityscape 144 framedagainst a blue sky 146. This and other tracks, having differentconfigurations or objectives, e.g., teaching the user 102 how to pursueother cars in traffic, can be selected by the user 102 or downloaded,preferably by an instructor, from the personal computer 103. Since thepresently preferred system 100 of the present invention does not use atimer or score points, the user 102 will not feel a need to drive asfast as possible, but instead, will concentrate on learning propertechnique.

FIG. 3 illustrates the flow diagram for the top-level function of thecontrol process 120 (FIG. 1) called "executive₋₋ control". In onepresently preferred embodiment, the control process 120 is written inthe "C" language and cross-compiled using a Green Hills Software, Inc."C" compiler available from Oasys, a division of Xel, Inc. of Waltham,Mass. The control process 120 is then executed on a Motorola 68000microprocessor located in the computer 114. However, one skilled in theart of computers will recognize that many other computer languages andcomputers, including pluralities of each, may be used to achieve thesame result. Computer source code of relevant portions of the controlprocess 120 is attached herewith in the accompanying MicroficheAppendix. A portion of the source code that executes on the 68000microprocessor is listed in the Microfiche Appendix with the title:rpath.c. Another portion of the source code that executes on the 68000microprocessor is listed in the Microfiche Appendix with the title:pursuit.c.

Prior to a start state 220, a program is downloaded from the computer103 to the computer 114. The user 102 (FIG. 1) then presses anabort/select rocker switch (not shown) which is one of the column anddash switches 105. Moving to a state 222, the computer 114 (FIG. 1)directs the video display 122 to display a series of menus from whichthe user may, depending on the program that is being run by the computer114, select the type of car, or the type of weather. The selection isaccomplished by manipulating one or more of the rocker switches (notshown) which are part of the dash and column switches 105. In some ofthe scenarios or programs that will be downloaded from the computer 103,a series of default choices will be made for the type of vehicle andweather. After selections are made for vehicle and weather, if desired,or the default choices are accepted, the user 102 selects the "startscenario" option and then manipulates a rocker switch (not shown) tosignal the computer 114 to move to the next state.

The computer 114 (FIG. 1) then moves from the state 222 to a state 224where the computer 114 will initiate a process by which the pathfollowed by the observer vehicle in the upcoming scenario will berecorded. This recording can be played back at a later time to permitanalysis and critique of the performance of the use during the scenario.The computer 114 moves from the state 224 to a state 226 wherein thecomputer 114 will perform a loop until the abort/select switch ispressed up (abort) or the user 102 has crashed. The loop, encompassing aseries of states 226 through 248, is preferably completed by thecomputer 114 sufficiently quickly so that position information can bedisplayed in real-time providing the observer car and environment withfluid movement effects on the video screen 122, the speakers 123, 124,and the low frequency speaker 430.

At a state 228, the position of the observer car is obtained from themodel process 116 (FIG. 1). The model process 116 calculates the lastposition of the observer car based upon the user's inputs which occurasynchronously. Moving to the next state 230, the computer 114 generatesoutput signals including sounds via the speakers 123 and 124, road feelcues via the speaker 430, vibrations on the steering wheel 112 andpulsations on the brake pedal 106 via the ABS system 500.

Next, at a decision state 232, a determination is performed by thecomputer 114 (FIG. 1) whether the user has selected or been assigned toa cone course. A cone course is a course where the user 102 will drivean automobile on a track containing cones. If a cone course has beenselected or assigned, the computer 114 moves on to a "cones" function234 wherein the user 102 is given choices on performance feedback. If acone course was not chosen as determined by state 232, the computer 114proceeds to state 236. At state 236, if the user 102 has selected orbeen assigned one of the pursuit tracks wherein the user 102 is requiredto pursue a specific automobile, the pursuit car, through the simulateduniverse, the recorded position of the pursuit car is updated. Thismeans that the pursuit car is placed in a certain position in thegraphical universe or environment 139 (FIG. 2) prior to the displaysystem of the computer 114 (FIG. 1) actually updates the video display122. Next, at a state 238, the recorded position of the observer car,the car doing the pursuing, is updated by being placed in a certainposition in the graphical universe 139. The computer 114 then moves to adecision state 240 where the computer 114 checks to see whether anabort/select rocker switch has been pressed up (abort) or the simulatedvehicle has crashed.

Next, moving to a "display₋₋ objects" function 242 if the abort switchwas not pressed or the car has not crashed, a display command isinitiated to the digital signal processor (not shown) in the computer114 (FIG. 1), such as the ADSP-2101 chip available from Analog Devicesof Norwood, Mass. In this function 242, display objects, such as thetrack, background (houses, etc.), the pursuit car (if on a pursuittrack) and the observer car, are appropriately translated in thegraphical universe 139 (FIG. 2) according to the perspective of the user102, for later display on the video display 122.

Moving to a state 244, the instrument panel 130, including thespeedometer, turn signal indicators, and various indicator lights, isupdated. A separate fuel gauge (not shown) is also updated. Then, at astate 246, collision sounds, sounds associated with the observer carcolliding with barriers, cones, buildings and the like, are generated ifthe computer 114 determines that the simulated vehicle has collided withsomething. At a state 248, the video display 122 has itsthree-dimensional graphics display updated by a command being issued tothe graphics signal processor such as, for example, the 34010 chipdistributed by Texas Instruments, which can handle color filledthree-dimensional graphics in real-time. Following the state 248, thecomputer 114 moves to state 226 to begin the next pass of the loop.Returning to the decision state 240, if abort is selected or if thesimulated car has crashed, the current session is terminated and thecomputer 114 proceeds to state 222 to begin a new session.

The instrument panel 130 of the system 100, as shown in FIG. 4, includesa speedometer 302, a transmission gear indicator display area 304, atransmission gear indicator 306, a indicator and warning light area 308.Several input devices of the system 100, including the turn signal lever104, the automatic transmission or shift lever 110, and the steeringwheel 112, are also shown. The speedometer 302 and indicators becomeactive when the user 102 (FIG. 1) "starts" the simulated vehicle. Thespeedometer 302 provides a measurement of velocity. The gear indicator306 visually displays the position of the shift lever 110 upon the gearindicator display area 304. The indicator and warning light area 308includes the following designators (left to right): left turn signal308a, temperature, battery, seat belt, brake, oil pressure, high beam(headlights), emergency flasher, and right turn signal 308b. The turnsignal lever 104 is mounted on a steering column housing 310.

FIG. 5 is a side elevational diagram of one preferred embodiment of aseat and low frequency speaker assembly 400 shown in partialcross-section. The purpose of the assembly 400 is to provide the user102 (FIG. 1) with meaningful and realistic road feel cues. The assembly400 includes a seat 402, preferably made of a light weight plastic orupholstered wood, upon which the user 102 will sit while operating thesystem. The seat 402 is movably mounted on a housing 404, preferablymade of thick metal, containing a seat adjust mechanism (not shown). Theseat adjust mechanism can be of any type known in the art which permitsthe user 102 to adjust the seat 402 into a preferred position relativeto the driving controls (not shown). Seat adjustment is accomplished bythe user 102 manipulating a seat adjust control 406.

The seat adjust mechanism housing 404 is attached to the top of amounting post, generally indicated by the reference numeral 408. In thispreferred embodiment, the mounting post 408 is cylindrical andpreferably made of a solid material such as stainless steel, with a topportion 409 and a bottom portion 410, the bottom portion 410 having asmaller diameter than the top portion 409. A cylindrical bearing 412 ismounted flush on the bottom portion 410 of the mounting-post 408.

The bottom portion 410 of the mounting post 408 extends through amounting hole 414 (FIG. 6) in a swivel base 416. The mounting hole 414is preferably 4 inches in diameter which is slightly larger than theouter diameter of the bottom portion 410 of the mounting post 408. Thebearing 412 is mounted on the bottom portion 410 of the mounting post408 such that when the bottom portion 410 extends through the mountinghole 414 the upper surface of the bearing 412 will be positioned betweenthe upper portion 409 and the upper surface of the swivel base 416. Thebearing 412 can be of any type known in the art which will facilitateswiveling the seat 402. The swivel base 416 is preferably made ofstainless steel and is flushly mounted on top of a seat mounting plate420 and is primarily secured thereto by four screws 422 (two shown)which extend through the seat mounting plate 420 into a semi-rigiddiaphragm 424.

A securing member 426 is attached to the bottom portion 410 of themounting post 408 underneath the swivel plate 416, such that thesecuring member 426 prevents the mounting post 408 from being lifted outof the mounting hole 414 while still permitting the seat 402 to swivel.A person skilled in the art can appreciate that the securing member 426can be comprised of a nut and lock washer used in combination withthreads on the bottom portion 410 of the mounting post 408 or any othercombination which secures the mounting post 408 in the described fashionwhile still permitting the seat 402 to be swiveled.

The swivel plate 416 is attached to the seat mounting plate 420, whichis preferably a 16 inch by 18.75 inch piece of 3/4 inch thick plywoodwith beveled edges. The seat mounting plate 420 is further attached tothe semi-rigid diaphragm 424. The semi-rigid diaphragm 424 is preferablya 29.80 inch by 35.50 inch piece of 1/2 inch or 3/8 inch thick plywood,the top of which is covered by corrugated rubber matting 425 (FIG. 6)suitable for providing secure footing for the user 102. The semi-rigiddiaphragm 424 must be sufficiently flexible so that it can vibrate inresponse to changes in air pressure induced by the low frequency audiospeaker 430 positioned on an adjacent enclosure 428. The operation ofthe speaker 430 and the enclosure 428 will be discussed in greaterdetail below.

Connected to the bottom side of the semi-rigid diaphragm 424, at itsoutside edges, are four vertical support members 432 (two shown). Thevertical support members 432, are preferably made from 3/4 inch thickparticle board, and they are connected to the semi-rigid diaphragm 424along its outside perimeter so that they extend perpendicularlydownward. Connected to the bottom surfaces of the vertical supportmembers 432 is a horizontal support member 434, preferably made from 3/4inch thick particle board, which serves as a base plate for the assembly400. The length and width dimensions of the horizontal support member434 are substantially identical to the dimensions of the semi-rigiddiaphragm 424 such that when the semi-rigid diaphragm 424, the verticalsupport members 432 and the horizontal support member 434 are assembled,they form a rectangular box-like structure. Also mounted to the bottomside of the semi-rigid diaphragm 424, parallel to, and insetapproximately one inch from each of its outside edges are four cleats436 (two shown). The four cleats 436 preferably consist of lengths ofmahogany wood with a 3/4 inch square cross section. Where the cleats 436intersect near the corners of the semi-rigid diagram 424, they arepreferably joined to each other in a substantially air-tight fashion.

Attached to the bottom side of the cleats 436, in a substantiallyair-tight fashion, is a speaker member 440. The speaker member 440 ispreferably a 27.80 inch by 33.50 inch rectangular piece of 3/4 inchthick particle board. The speaker member 440 further contains a circularhole 442 with approximately a 7 inch diameter. The speaker 430 ismounted to the underside of the speaker member 440, preferably in asubstantially air-tight fashion, so that the diaphragm of the speaker430 is substantially centered about the hole 442 and is exposed to theair within the enclosure 428. The enclosure 428 is thereby formed by thesemi-rigid diaphragm 424, the cleats 436, the speaker member 440, thespeaker 430, and the swivel base 416. Preferably, the enclosure 428 isair-tight, however, perfect air-tight integrity is not a requirement forthe operation of the assembly 400. In this presently preferredembodiment, the speaker 430 is a model QUAM--NICHOLS, eight inch, 8 Ohm,50 Watt two terminal woofer speaker part number 92-9846.

FIG. 6 is a top plan view of the base portion of the seat and speakerassembly, taken along line 6--6 of FIG. 5. FIG. 6 selectively shows therelative mounting locations and sizes of some of the members whichcomprise the base containing the speaker 430 and the enclosure 428 ofthe presently preferred embodiment. For purpose of clarity in thedescription below, two direction arrows 444 and 446 are shown in FIG. 6.The mounting hole 414 in the plate 420 is preferably offset from thecenter of the plate 420 by approximately 4 inches in direction of thearrow 446 and approximately 3 inches in the direction of arrow 444. Themounting post 408 (shown in FIG. 5), extends perpendicularly outwardfrom hole 414 and is preferably coupled to the seat adjust mechanismhousing 404 (shown in FIG. 5) offset from the center of the housing 404in the same direction as the arrow 444 by the same distance as themounting hole 414 is offset in the direction of the arrow 444 from thecenter of the plate 420.

When the seat 402 is oriented in its nominal operational position,facing in the opposite direction as the arrow 446, as shown in FIG. 5,the seat 402 will be located such that it is centered over the seatmounting plate 420 in the direction of the arrow 444 while being offsetapproximately 4 inches from being centered over the plate 420 in thedirection of the arrow 446. Positioning the seat 402 in this fashionpermits easier access to the seat 402 by the user 102 as the seat 402can be swiveled so when the seat 402 faces in the direction of the arrow444, the edge of the seat 402 will preferably extend beyond the edge ofthe semi-rigid diaphragm 424. FIG. 6 also shows the locations of fourholes 423 for the four screws 422 which secure the swivel plate 416 (seeFIG. 5) to the seat mounting plate 420 and to the semi-rigid diaphragm424. The speaker hole 442 is located substantially at the center of thespeaker member 440 (FIG. 5). As shown in FIG. 6, the hole 442 is thenlocated in the speaker member 440 underneath and at the approximatecenter of the semi-rigid diaphragm 424. The top surface of thesemi-rigid diaphragm 424 is preferably covered by the corrugated rubbermatting 425, shown in part in FIG. 6. This matting 425 is preferablyfixedly attached to the semi-rigid diaphragm 424 through the use oftacks or glue. Also shown in FIG. 6 are the cleats 436, mountedunderneath the semi-rigid diaphragm 424, which are also shown to meetand join each other at their ends.

The basic operation of the assembly 400, will now be explained byreferring again to FIG. 1. The control process 120 receives input fromthe model process 116 indicating that an event, e.g., collision with anobject, engine vibration and so forth is occurring. In response, thecontrol process 120 access a digital representation of a signal in awave table (not shown) stored in one of the RAMs of the computer 114.The wave table stores a well-known digital representation of thefrequency content, the amplitude and the duration of the signalscorresponding to various events, e.g., collision with specific objects,engine noise. Once a digital representation is accessed, the controlprocess 120 then reproduces the digital representation and causes itstranslation into an analog signal representative of the specific eventwhich is then fed to the low pass filter 454. Computer source code ofrelevant portions of the control process 120 which accesses the digitalsignal is attached herewith in the accompanying Microfiche Appendix.

The filter 454 is a low pass filter with a frequency response of 20 to80 Hertz (Hz), hence, only signals with a frequency content below 80 Hzwill be passed by the filter 454 to the amplifier 450. The amplifier 450is a 28 Watt power amplifier capable of producing a 24-volt,peak-to-peak output signal at maximum gain. Hence, the amplifier 450increases the amplitude of the low frequency signal it receives from thelow pass filter 454 and feeds this amplified low frequency signal to therelay 452.

The relay 452 is designed to protect the speaker 430 from damage causedby voltage spikes generated by either powering up or powering down thesystem 100. As is understood in the art, oftentimes when electronicequipment is in a period of power transition, transient voltage spikesare generated which, if transmitted to audio-speakers of a type similarto speaker 430, can result in damage to the speakers. Even if thesetransients do not damage the speaker 430 they may unsettle the user 102sitting in the seat 402. Consequently, the relay 452 is connected to thecontrol circuit 456, described below, which will disconnect the speaker430 from the electrical circuitry of the system 100 during periods ofpower transition.

Referring now to FIGS. 1, 5 and 6, when the system 100 is not in aperiod of power transition, the relay 452 will send the high amplitude,low frequency signal received from the amplifier 450 to the speaker 430.The diaphragm of the speaker 430 will then vibrate in response to thehigh amplitude, low frequency signal, thereby displacing the air withinthe enclosure 428. This displacement of the air within the enclosure 428causes the semi-rigid diaphragm 424, which shares common structuralcomponents with the enclosure 428, to bounce or vibrate. The vibrationof the semi-rigid diaphragm 424 is then communicated through the seatmounting plate 420 and the seat mounting post 408 to the seat 402 andthen to the user 102. In this fashion, events such as engine vibration,hitting an object, and so forth can be realistically represented to theuser 102 of the simulation system 100.

For example, to simulate the feel of hitting a cone while driving thesimulated car on the course 142 shown in FIG. 2, the control process 120retrieves a wave sample of the sound from the wave table (not shown) andfeeds the equivalent analog signal, having a sharp low frequency peak tothe filter 454. The filter 454 passes the low frequency content (below80 Hz) of the signal to the amplifier 450. The amplifier 450 increasesthe amplitude of the signal and passes it to the relay 452. This highamplitude signal will then be sent to the speaker 430 if the system 100is not in a period of power transition. The speaker 430 communicates ahigh excursion pulse through to the air within the enclosure 428 byvibrating the diaphragm of the speaker 430. The resulting displacementand consequent compression of air within the enclosure 428 istransmitted to the semi-rigid diaphragm 424 and ultimately to the user102 sitting on the seat 402. The user 102 will then experience a quickjolt to simulate the feel of hitting the cone as the speaker diaphragmmoves the air in the enclosure 428.

The control process 120 can cause different samples of sound stored inthe wave table to be transmitted, in the above-described fashion, to theuser 102 for a single event. The low frequency signal generated by thecontrol process 120 for a cone collision may have a duration in therange of 100 milliseconds to one second. Other signals, such as thosedefining engine vibration may have longer duration. By increasing thenumber of sound samples stored in the wave table, many other road feelcues may be utilized by the system 100. During the same event thecontrol process provides independent signals to the speakers 123 and 124which are indicative of engine noises, cone collisions and so forth.Included in the Microfiche Appendix is the source code used by thecontrol process 120 to implement the operation of the wave table hereindescribed.

The relay control circuit 456 is more fully described by reference toFIG. 7. The relay control circuit 456 is designed to turn the relay 452off during periods of power transition, e.g., when powering up and whenpowering down the system 100. The circuit 456 is designed so that whenthe actual voltage for the system 100 falls below its normal inputvoltage, preferably 12 VAC, the relay 452 will disconnect the input tothe speaker 430 from the output of the amplifier 450. The operation ofthe circuit 456, shown in FIG. 7 will now be described.

When the system 100 is turned on, an actual voltage is input to a diode457, this voltage then begins to charge a capacitor 460 coupled to thenon-inverting input (+) of a comparator 464. Simultaneously, a capacitor463, which is connected to the inverting (-) input of the comparator 464is charged by a reference voltage (Vref), preferably 14 volts, through aresistor 462. A capacitor 470, which is connected to the non-inverting(+) input of a comparator 473, is also charged by the supply voltage(Vsupply) through a resistor 469. When the voltage on the non-inverting(+) input of the comparator 464 exceeds the voltage on the inverting (-)input of the comparator 464, the comparator 464 outputs a high voltagewhich causes slow charging of capacitor 472 and that appears on theinverting (-) input of comparator 473. When the voltage on the inverting(-) input of the comparator 473 exceeds the voltage on the non-inverting(+) input of comparator 473, the output of the the comparator 473 goeslow will then energize the coil of the relay 452 thereby connecting thespeaker 430 to the amplifier 450.

When the power to the system 100 is turned off, the circuit 456 operatesas follows. The capacitor 460 rapidly discharges dropping the voltage onthe non-inverting (+) input of the comparator 464 beneath the voltage onthe inverting (-) input of comparator 464 and thereby turning thiscomparator off. Consequently, a voltage on the inverting (-) input ofthe comparator 473 will decrease. This results in the comparator 473turning off as the voltage on the non-inverting (+) input of comparator473 is greater than the voltage on the inverting (-) input. With thecomparator 473 turned off (goes high), the coil of the relay 452 isde-energized, which results in the relay 452 disconnecting the speaker430 from the amplifier 450.

Preferably, when the system 100 is powering up, the circuit 456 willdelay energizing the coil of the relay 452 to connect the speaker 430 tothe amplifier 450 for a relatively long time, preferably approximately 4seconds, thereby permitting any transients which would cause damage tothe speaker 430 to dissipate. However, after the system 100 is powereddown, it will be desirable to quickly disconnect the coil of the relay452 from the amplifier 450, preferably within approximately 16milliseconds, to prevent any transients being transmitted to the speaker430. Values of one presently preferred embodiment of the component partsof circuit 456 are shown in Table 1 below. When used in the circuitconfiguration shown in FIG. 7, a suitably long delay turn-on time with asuitably quick turn-off time is achieved.

                  TABLE 1                                                         ______________________________________                                                              PART                                                    IDENTIFIER PART       NUMBER    VALUE                                         ______________________________________                                        464        Comparator LM311     --                                            473        Comparator LM311     --                                            457        Diode      IN4001    --                                            474        Diode      IN4001    --                                            458        Resistor   --        10kΩ                                    459        Resistor   --        4.7kΩ                                   461        Resistor   --        470Ω                                    462        Resistor   --        10kΩ                                    466        Resistor   --        82kΩ                                    467        Resistor   --        270Ω                                    469        Resistor   --        4.7kΩ                                   471        Resistor   --        2.2 μF                                     460        Capacitor  --        2.2 μF/50VμF                            463        Capacitor  --        0.1 μF                                     470        Capacitor  --        0.1 μF                                     472        Capacitor  --        0.1 μF                                     465        Capacitor  --        47 μF                                      468        Capacitor  --        0.1 μF                                     ______________________________________                                    

FIG. 8 is a side elevational diagram showing a cross section of anotherpreferred embodiment of a seat and low frequency speaker assembly 480.The purpose of the assembly 480 is also to provide the user 102 (FIG. 1)with meaningful and realistic road feel cues. The assembly 480 includesa seat 482 that has at least a portion of its interior hollow with arecess 484. The recess 484 has the low frequency speaker 481 which isconnected to the simulation system 100 in the same manner as is thespeaker 430 (FIG. 1) mounted and secured such that a diaphragm of thespeaker 481 is in communication with the air that is enclosed in theenvelope or bladder 486 of the seat. The diaphragm of speaker 481 movesback and forth in a conventional manner in response to a signalpresented at the speaker terminals. This back and forth motion iscommunicated through the air creating vibration on the surfaces 488 ofthe seat 482. The surfaces 488 are made of a somewhat flexible butstrong plastic material. The back and bottom surfaces are somewhatthicker and hence stiffer, while the surfaces in contact with the user102 (FIG. 1) are thinner to flex in response to the vibration of theair. The surfaces in contact with the user 102 may be overlaid with acover and cushion 489.

The speaker 481 of this presently preferred embodiment is a model40-1348 dual-coil eight inch speaker sold by Radio Shack. The speaker481 has four terminals, a first set of terminals 490 is visible in FIG.8. The speaker 481 is fastened to the seat 482 by four bolts, thelocations of two are indicated by a pair of holes 483a and 483b. Thespeaker 481 is connected to the control process 120 (FIG. 1) of thesystem 100 through the relay 452, the amplifier 450, and the low passfilter 454 in the same fashion as was the speaker 430 in the preferredembodiment shown in FIGS. 5 and 6 and it receives signals indicative ofroad feel cues in the same fashion as described above.

FIG. 9 shows a cross-sectional view of the ABS brake pedal system 500with the attached brake pedal 106 of the preferred embodiment of thepresent invention shown in FIG. 1. The ABS brake pedal system 500 ismechanically arranged so that the brake pedal 106 provides for movementwhich simulates the movement of a brake pedal in a real automobile.

The ABS brake pedal system 500 includes a mounting plate 502 having aback side 503 and a front side 505. The mounting plate includes aplurality of mounting holes 504 (two shown) through which screws (notshown) are used to secure the ABS brake pedal system 500 to the housing(not shown) of the simulator system 100 in a similar orientation asbrake pedals in a typical automobile.

A connector rod 506 extends through a hole in the mounting plate 502.The portion of the connector rod 506 extending out from the back side503 of the mounting plate 502 is preferably threaded. Coupled to thethreaded portion of the connector rod 506 is a washer 508 which ispositioned on the connector rod 506 so as to be sitting adjacent to theback side 503 of the mounting plate 502. A cylindrical elastic bumper510 having an opening slightly larger than the diameter of the connectorrod 506, and a spring 512 are both positioned on the threaded portion ofthe connector rod 506 adjacent to the washer 508. The inner diameter ofthe spring 512 is slightly larger than the outer diameter of the bumper510 so that when the bumper 510 is positioned on the connector rod 506,the spring 512 is then mounted over the bumper 510. A washer 514,capable of retaining and compressing the spring 512, is also positionedon the connector rod 506 so that the spring 512 and the elastic bumper510 are positioned in axial alignment with the connector rod 506 betweenthe washer 514 and the washer 508. The spring 512 is longer than theelastic bumper 510 so that the spring 512 will have to be compressedbefore the elastic bumper 510 can make contact with both of the washers508 and 514 at the same time. A nut 516 adjustably secures the washer514 to a specified position on the connector rod 506.

The portion of the connector rod 506 which projects out from the front505 of the mounting plate 502 is connected to a cross piece 518 which,in turn, connects two identical force multiplier arms 519 (one shown).An elastic rebound bumper 520 is positioned on the portion of theconnecting rod 506 between the mounting plate 502 and the cross piece518. The top end of each of the force multiplier arms 519 isrespectively bolted to one of two arms 521 of an electrically controlledsolenoid 522 in such a manner that when current is supplied to thesolenoid 522, the force multiplier arms 519 move in response thereto.

An adjustment screw 528 is also mounted on another cross-piece (notshown) connected between the force multiplier arms 519. The adjustmentscrew 528 extends through the cross piece connecting the forcemultiplier arms 519 to a lever arm 526. The adjustment screw 528 permitsthe user 102 to adjust the amount of motion of the force multiplier arms519, relative to the lever arm 526, induced by the solenoid 522. Hence,tightening the adjustment screw 528 will decreases the amount by whichthe force multiplier arms can travel relative to the lever arm 526. Thebottom ends of both of the force multiplier arms 519 are connected via abolt 532 and a nut (not shown) to a brake pedal member 530. The solenoid522 is secured to the top of a plate 524, the bottom surface of theplate 524 is, in turn, secured to a lever arm 526 which projectsperpendicularly downward from the plate 524.

The lever arm 526 is welded near its bottom end to the brake pedalmember 530 along the length of the lever arm 526 intersecting thesurface of the brake pedal member 530. A strain gauge 534 is preferablybonded to the material of the lever arm 526 in a position to sensestrain in the lever arm 526 as force is applied to the brake pedal 106.The strain gauge 534 is of conventional structure and may be either ofthe metallic or semiconductor type. The strain gauge 534 is essentiallya serpentine resistive path that will either elongate or shorten asstrain is applied to the lever arm 526 thereby resulting in a change ofresistance, which can be detected by an appropriate electrical circuitto be discussed below.

The brake pedal member 530 is a substantially L-shaped member whichinitially extends substantially downward from the force multiplier arms519 and then extends substantially outward from the mounting plate 502to where the brake pedal member 530 terminates in the brake pedal 106.The brake pedal 106 preferably is identical to typical brake pedals inreal automobiles. The brake pedal member 530 is also fixedly connectedto a pivot bearing member 538. The pivot bearing member 538 preferablycomprises a metal cylinder which is horizontally mounted between tworectangular securing members 540 (one shown) which are mounted on thefront side 505 of the mounting plate 502.

The mechanical operation of the ABS brake pedal system will now bedescribed in conjunction with FIGS. 1 and 9. In response to conditionsobserved from the simulator 100, the user 102 places his foot upon thebrake pedal 106 and depresses it in the same fashion as a driver woulddepress a brake pedal in an actual car. In response to the forceresulting from the user 102 depressing the brake pedal 106, the brakepedal member 530 pivots about the pivot bearing member 538 in thedirection of an arrow 542. This causes the segment of the brake pedalmember 530 above the pivot bearing 538 to be urged to move in thedirection depicted by an arrow 544. Since the segment of the brake pedalmember 530 above the pivot bearing 538 is coupled to the forcemultiplier arms 519, the force multiplier arms 519 will also be urged tomove in the direction of the arrow 544. Movement of the force multiplierarms 519 in the direction of the arrow 544 causes the connector rod 506attached thereto to also move in the same direction, which is thepositive X-direction in FIG. 9.

Since the connector rod 506 includes an attached washer 514 and nut 516,movement of the connector rod 506 in the direction of the arrow 544 alsoresults in movement of the washer 514 and nut 516 in the positiveX-direction. As the washer 514 is moved in the positive X-direction itcompresses the spring 512, which in turn causes linearly increasingforce to be exerted against the washer 514 in the negative X-direction.Eventually, the spring 512 will be compressed to the point where thewasher 514 will make contact with the elastic bumper 510. At that point,greater force will be exerted against the washer 514 in the negativeX-direction. When the user 102 stops depressing the brake pedal 106 inthe direction of arrow 542, the spring 510 will push the washer 514 andthe connector rod 506 in the negative X-direction to their initialposition, which will in turn cause the force multiplier arms 519, thebrake pedal member 530 and the brake pedal 106 to return to theirinitial undepressed position. As can be appreciated, the amount of forceexerted by the spring 512 and the elastic bumper 510 in opposition tothe user 102 depressing the brake pedal 106 in the direction of thearrow 542 can be adjusted by positioning the washer 514 at a differentlocation along the connector rod 506 and securing it thereto with thenut 516.

Depression of the brake pedal 106 in the direction of arrow 542 in thismanner also results in straining the lever arm 526 causing theserpentine resistive path of the strain gauge 534 to either shorten orlengthen thereby changing its measured resistance. The strain gauge 534is electrically connected to the control process 120 of the computer 114as shown in FIG. 1. As can be appreciated, additional electroniccircuitry is required to translate the change in resistive value of thestrain gauge 534 due to increased strain upon the lever arm 536 into anelectronic signal that the computer 114 can utilize. Consequently, thisembodiment of the invention includes a bridge/interface circuit 546 (seeFIG. 1) of a type available in the marketplace. Generally, theresistance of the strain gauge 534 changes very little during strain ofthe material of the lever arm 526, hence, the bridge/interface circuit546 includes bridge circuitry which may be used to detect the slightchanges in the resistance of the strain gauge 534. Further, thebridge/interface circuit 546 also includes interface circuitry whichwill convert the analog bridge circuit output signal to a digital formatsuitable for use by the control process 120. As can be appreciated byone skilled in the relevant technology, one of the difficulties of usingstrain gauges, and particularly sensitive silicon based strain gauges,is that these gauges have temperature drift characteristics which resultin inaccurate readings. It is desirable in the quiescent state when nostrain is being experienced by the lever arm 526 that the bridge bebalanced to minimize these effects.

Specifically, the presently preferred bridge/interface circuit issubstantially the same as the circuit shown in FIG. 9 of U.S. Pat. No.4,949,119 to Moncrief, et al. The desirability of using such a circuitwas described in this patent at Column 7, lines 3-60 and the manner inwhich this circuit operated, both as a balancing bridge and as a analogto digital converter is described in detail at Column 9, line 16 toColumn 10, line 32. U.S. Pat. No. 4,949,119 to Moncrief, et al., ishereby incorporated by reference.

The ABS brake pedal system 500, shown in FIG. 9, simulates the feelingthe user 102 will feel through his foot when he is depressing the brakepedal 106 with sufficient force such that an ABS braking system wouldtypically be activated in a real world automobile. As previouslydescribed, in this preferred embodiment, when the user 102 depresses thebrake pedal 106, a strain will be induced upon the lever arm 526 whichwill then be detected by the strain gauge 534. The strain gauge 534 iscoupled to the bridge/interface circuit 546 which detects and translatesthe signal detected by the strain gauge into a signal which can beprocessed by the computer 114, and specifically the control process 120.

If this signal indicates that the user 102 is depressing the brake pedal106 with substantially the same amount of force that would activate atypical ABS brake system in real-world automobiles, the control process120 sends a pulsating voltage signal to the solenoid 522. In response tothis pulsating voltage, the solenoid 522 will cause the solenoid arms521 to move back and forth in the positive and negative X-direction.This movement of the solenoid arms 521 causes the force multiplier arms519 to vibrate. Since the force multiplier arms 519 are connected to thebrake pedal member 530 which is in turn connected to the brake pedal106, vibration of the force multiplier arms 519 will ultimately be feltby the user 102 as he depresses the brake pedal 106. As can beappreciated by a person skilled in the technology, the amplitude of thisinduced vibration of the force multiplier arms 519 can be controlled bytightening or loosening the adjustment screw 528 attached thereto.Consequently, by adjusting the screw 528, the vibration felt by the user102 while depressing the brake pedal 106 can be made to approximate thefeeling of an actual brake pedal in an actual ABS equipped car when theABS brakes are being applied.

In this presently preferred embodiment, the control process 120 willcontinue to send the pulsating voltage to the solenoid 522 so long asthe simulated vehicle is still moving and the user 102 is stilldepressing the brake pedal 106 with sufficient force to initiate thepulsating voltage.

Included in the Microfiche. Appendix is the source code, entitled abs.c,used by the control process 120 to implement the operation of the ABSsystem herein described. The pulsating voltage preferably has a 40 msecpulse width with a cycle period of 100 msec.

The embodiments of the invention here-in-above have several significantadvantages over the prior art. Specifically, the simulation system thatApplicant has disclosed is capable of generating and transmitting a widevariety of road feel cues to the user of the simulator. These road feelcues can be stored and recalled when an event occurs within thesimulated universe which would normally trigger a specific road feel ina real world automobile, e.g. hitting a bump etc. and are transmitted tothe user by a mechanism which can accommodate and transmit a largenumber of feelings.

Further, the simulation system that Applicant has disclosed alsorealistically represents the feel that the vehicle controls would havewhen operating in the real world. Specifically, the driving embodimentof the present invention includes a steering wheel with feedback as wellas a brake pedal which simulates the feeling of ABS brakes. A simulationsystem with these features provides a more realistic representation ofthe real world, and a such, provides a better educational experience ofhow to operate this vehicle in the real world.

Although the above detailed description has shown, described and pointedout fundamental novel features of the invention as applied to thevarious embodiments discussed above, it will be understood that variousomissions and substitutions and changes in the form and details of thedevice illustrated may be made by those skilled in the art, withoutdeparting from the spirit of the invention. The described embodimentsare to be considered in all respects only as illustrative and notrestrictive.

What is claimed is:
 1. A low frequency sound system of a vehiclesimulation system for simulating the physical sensation representativeof the sensations produced during the operation of the simulatedvehicle, comprising:a seat, wherein a user of the simulated vehicle sitsduring operation of the simulated vehicle; a plurality of input devicecorresponding to input devices of the vehicle simulated by the vehiclesimulation system; a computer for receiving input signals from the inputdevices; a control process executed by the computer for selectivelyconverting the input signals into a plurality of control output signals,wherein the plurality of control output signals correspond to aplurality of events occurring during operation of the simulated vehiclein simulated universe; and a transducer responsive to the control outputsignals for communicating a plurality of low frequency output signals tothe seat, wherein each of the plurality of low frequency output signalsproduce a corresponding physical motion of the seat so as to provide theuser with a physical sensation that corresponds to one of the pluralityof events occurring during the operation of the simulated vehicle in thesimulated universe.
 2. A vehicle simulator for modeling physicalsensations produced by occurrence of physical events during theoperation of the simulated vehicle in the simulated universe,comprising:a plurality of input devices for controlling the operation ofa simulated vehicle; a controller which receives signals from at leastone of said plurality of input devices that direct said simulatedvehicle through a simulated universe wherein at least one of saidplurality of simulated physical events occur by said simulated vehiclein a simulated universe; a computer, responsive to the controller, fordetermining position information of the simulated vehicle in saidsimulated universe and for providing a signal representing occurrence ofa simulated physical events during operation of said simulated vehiclein said simulated universe; and a low frequency sound system, having aspeaker positioned in the proximity to a user and responsive to thesignal produced by the computer, for communicating a of frequency soundsignal from the speaker which produces a physical sensation felt by theuser that is representative of a sensation that said user would detectupon actual occurrence of the simulated physical event occurring duringthe operation of the simulated vehicle in the simulated universe.
 3. Asimulator as defined in claim 2, further comprising a surfacepositionable in physical contact with the user and responsive to thesound signal such that said surface communicates said physical sensationto said user.
 4. A simulator as defined in claim 2, wherein the computerselects one of a plurality of sound signals stored in a memory inresponse to the determined position information, and provides theselected signal to the speaker of said low frequency sound system.
 5. Asimulator as defined in claim 4, further comprising a video displayresponsive to the signals from the computer for providing the user witha view of the simulated universe.
 6. A simulation system for a user of asimulated vehicle for providing simulated physical sensationsrepresentative of the sensations produced during the operation of thesimulated vehicle, comprising:a plurality of simulated input devices forcontrolling the operation of the simulated vehicle; modeling meansresponsive to the input devices for determining position information ofthe simulated vehicle in a simulated environment; a video display forpresenting the user with a view of the simulated environment as seenfrom said simulated vehicle; and means, responsive to the positioninformation of the simulated vehicle in said simulated environment, forproviding to the user a selected low frequency sound signal representingoccurrence of a simulated physical event during operation of saidsimulated vehicle in said simulated environment, wherein said lowfrequency sound signal is selected from a plurality of low frequencysound signals stored in a signal storing means and wherein each of saidlow frequency sound signals is configured to produce a physicalsensation that is sensed by the user and which is representative of asensation produced during operation of a corresponding actual vehicle ina corresponding actual position and in a corresponding actual universe.7. The simulation system of claim 6, wherein the low frequency soundsignal providing means comprises:means for processing the selected lowfrequency sound signal retrieved from the signal storing means; andmeans for transducing the selected low frequency sound signal receivedfrom the processing means into low frequency sound.
 8. The simulationsystem of claim 7, wherein the plurality of low frequency sound signalsinclude signals representative of the physical sensation of thesimulated vehicle colliding with an object in the simulated evironment.9. The simulation system of claim 7, wherein the plurality of lowfrequency sound signals comprises a plurality of digital signals andprocessing means comprises:a digital to analog converter receiving thedigital signals from the signal storing means; a filter receiving analogsignals from the converter; and an amplifier receiving a filteredsignals from the filter.
 10. The simulation system of claim 9, whereinthe filter is a low pass filter.
 11. The simulation system of claim 7,wherein the transducing means comprises:a speaker providing an audiosignal to a chamber; and a semi-rigid diaphragm connected to the chamberwhich vibrates in response to the audio signal.
 12. The simulationsystem of claim 6, wherein the plurality of low frequency sound signalsinclude signals representative of the physical sensation of thesimulated vehicle colliding with objects in the simulated environment.13. The simulation system of claim 12, wherein the simulated vehiclecomprises an automobile equipped with an engine and the plurality of lowfrequency sound signals include signals representative of the physicalsensation of the revving of the automobile engine.
 14. A simulationsystem for a user of a simulated vehicle for providing simulatedphysical sensations representative of the sensations produced during theoperation of the simulated vehicle, comprising:a plurality of simulatedinput devices for controlling operation of the simulated vehicle in asimulated universe; a computer, responsive to the plurality of simulatedinput devices, for determining position information of the simulatedvehicle in the simulated universe and for providing a plurality ofcontrol signals at least in part in response to the position informationof the simulated vehicle in the simulated universe; a video displayresponsive to the plurality of control signals for providing the userwith a view of the simulated universe as seen from the simulatedvehicle; and a low frequency sound system, having a speaker positionedadjacent to the user for providing the user with low frequency soundsignals that are configured to produce physical sensations experiencedby the user which are representative of physical sensations that occurduring operation of a corresponding actual vehicle in a correspondingactual universe, wherein the low frequency sound system responsive tothe control signals selects one of a plurality of low frequency soundsignals stored in the computer corresponding to the determined positioninformation, and provides the selected signal to the speaker.
 15. Thesimulation system of claim 14, wherein the simulated vehicle comprisesan automobile and the plurality of simulated input devices includes asteering wheel, an accelerator pedal, a gear shift, and a brake pedal.16. The simulation system of claim 14, wherein the plurality of storedlow frequency sound signals include signals representative of thephysical sensation produced by the simulated vehicle hitting a simulatedobject in the simulated universe.
 17. The simulation system of claim 16,wherein the simulated vehicle comprises an automobile containing anengine and the plurality of stored low frequency sound signalsrepresentative of the physical sensation of the revving of the engine.18. The simulation system of claim 14, wherein the vehicle simulatorincludes a seat mounted on a base for the user of the simulated vehicle.19. The simulation system of claim 18, wherein the base includes anenclosure and the diaphragm of the speaker is positioned adjacent theenclosure so that when the speaker transmits a low frequency signalrepresentative of a physical sensation produced by the operation of thesimulated vehicle, the air contained within the enclosure is displacedcausing the seat mounted on the base to vibrate.
 20. The system of claim18, wherein the seat includes an interior hollow enclosure located inthe back of the seat, said hollow enclosure containing a bladder, andwherein the speaker is mounted in the back of the seat adjacent thebladder so that when the speaker transmits a low frequency signalrepresentative of a physical sensation produced by the operation of thesimulated vehicle, the air contained within the bladder is displacedcausing the seat to vibrate.
 21. A simulation system including asimulated vehicle for providing simulated physical sensationsrepresentative of the sensations produced during the operation of thesimulated vehicle, the system comprising:a plurality of simulated inputdevices for controlling the operation of the simulated vehicle; acomputer, responsive to the plurality of simulated input devices, fordetermining position information of the simulated vehicle in thesimulated universe and for providing a plurality of control signals inresponse to the determined position information; a video display,responsive to the plurality of control signals, for providing the userwith a view of the simulated universe as seen from said simulatedvehicle as the simulated vehicle moves through the simulated universe;and a low frequency sound feedback system, having a low frequencyspeaker positioned adjacent to the user for providing the user with lowfrequency sound signals producing a physical sensation representative ofa physical sensation produced during operation of an actual vehicle inconditions corresponding to those influencing operation of the simulatedvehicle in an actual universe, wherein the low frequency sound feedbacksystem responsive to the control signals selects one of a plurality oflow frequency sound signals stored in the computer corresponding to thedetermined position information and provides the selected signal to thelow frequency speaker thereby producing the physical sensation.
 22. Thesimulation system of claim 21, wherein the plurality of stored lowfrequency sound signals include signals representative of a physicalsensation produced by the simulated vehicle hitting a simulated objectin the simulated universe.
 23. The simulation system of claim 21,wherein the simulated vehicle comprises an automobile containing anengine and the plurality of stored low frequency sound signals includesignals representative of the physical sensation of the revving of theengine.
 24. The simulation system of claim 21, wherein the vehiclesimulator includes a seat mounted on a base for the user of thesimulated vehicle.
 25. The simulation system of claim 24, wherein thebase includes an enclosure and the diaphragm of the low frequencyspeaker is positioned adjacent the enclosure so that when the lowfrequency speaker transmits a low frequency signal, the air containedwithin the enclosure is displaced causing the seat mounted on the baseto vibrate.
 26. The simulation system of claim 24, wherein the seatincludes an interior hollow enclosure located in the back of the seat,said hollow enclosure containing a bladder, and wherein the lowfrequency speaker is mounted in the back of the seat adjacent to thebladder so that when the low frequency speaker transmits a low frequencysignal, the air contained within the bladder is displaced causing theseat to vibrate.